EPA Screens 1,000 Chemicals Using ToxCast

WASHINGTON— The U.S. Environmental Protection Agency’s (EPA) ToxCast screening program has entered a new phase, screening 1,000 chemicals for potential toxicity to people and the environment. ToxCast is designed to determine how chemical exposures impact the human body and how the chemicals most likely lead to health effects. When fully implemented, ToxCast will be able to screen thousands of chemicals in fast, cost-effective tests that provide people with relevant information.

“ToxCast integrates revolutionary advances in molecular biology, chemistry and computer science to quickly and cost-effectively screen chemicals,” said Dr. Paul Anastas, assistant administrator of EPA’s Office of Research and Development. “This ground-breaking approach to chemical toxicity testing allows us to start predicting potential toxicity to human health and the environment instead of just describing the toxic effects that occur after chemical exposure.”

During the first phase ToxCast tested about 300 chemicals, primarily pesticides, in more than 500 fast, automated tests or assays. The assays use human and animal cells and proteins to screen chemicals. Another 700 chemicals are now being screened in ToxCast’s second phase. The chemicals being tested are found in industrial and consumer products, food additives and drugs that never made it to the market. The failed drugs and associated human clinical trial data, donated by major pharmaceutical companies, are significant because EPA will be able to compare ToxCast screening data to human clinical data and other toxicology studies.

Only a small fraction of the tens of thousands of chemicals in commerce have been adequately assessed for potential risks to human health and the environment. ToxCast is reducing EPA’s reliance on slow and expensive animal toxicity tests, enabling the agency to screen chemicals more quickly and to predict and identify potential health risks.

EPA scientists have compared the first phase of ToxCast data to the vast number of animal studies available in EPA databases. This comparison is helping determine which ToxCast assays can accurately predict different types of toxicity and disease. EPA scientific studies using ToxCast have already been published in peer-reviewed science journals and demonstrate the ability of ToxCast to predict a chemical’s potential to cause a variety of diseases.

The ToxCast research project is a substantial contributor to the federal agency collaboration, Tox 21. Comprised of EPA, U.S. Food and Drug Administration, and the National Institutes of Health, Tox21 will screen 10,000 chemicals by the end of next year.